KR20090100766A - A radio communication system and method for multicasting - Google Patents

Abstract

PURPOSE: A radio communication system supporting multicasting and a method thereof are provided to reduce delay time due to overlapped packets in a network when providing a multimedia data service. CONSTITUTION: A radio communication system supporting multicasting comprises a terminal(106) and a base station(104). The terminal receives an MCA-REQ(Multicast assignment request) message. The terminal checks an IP address of a multicast packet from the received MCA-REQ message. The terminal determines whether the checked IP address of the multicast packet is the same as an IP address of a service server which provides a multicast packet to be received. If the checked IP address of the multicast packet is the same as the IP address of the service server which provides a multicast packet to be received, a response signal corresponding to the received multicast packet is transmitted to a base station.

Description

Wireless communication system and method that supports multicasting {A RADIO COMMUNICATION SYSTEM AND METHOD FOR MULTICASTING}

TECHNICAL FIELD The present invention relates to wireless communication systems, and more particularly, to a wireless communication system and method for supporting multicasting.

IP multicast (hereinafter, referred to as 'multicast') refers to a method of transmitting the same data to the same multicast group subscribers at the same time so as to efficiently use network resources.

In the case of multicasting in a conventional wireless communication system, multicasting is implemented using a broadcasting method, or after a key is assigned to a terminal subscribed to a specific multicasting group, The multicast packet can be decoded to transmit the multicast packet only to the terminals of the group. However, such a method has a problem in that it takes a long time as the key is allocated and managed and the corresponding multicast packet is decrypted through the key.

 In addition, conventionally, a multicast packet may be transmitted to each member of a multicast group using a unicasting method, which is a one-to-one transmission method. The network bandwidth may be wasted because it may be duplicated and transmitted to the UE. In addition, when multiple unicasting occurs, as the number of terminals joined to the multicast group increases, the network traffic from the control station to the terminal increases in a huge amount. Therefore, a user who is provided with a time delay sensitive service such as multimedia or voice service may not be able to use the service properly.

Meanwhile, in order to transmit a multicast packet using the multicast method, there must be support of the data link layer for multicasting. In other words, in order to transmit a multicast packet to a corresponding destination, the MAC layer, which is a data link layer, must be supported. In Ethernet, a multicast IP address (Internet Protocol Address) and a 48-bit (bit) MAC address are mapped to each other to transmit a multicast packet to a corresponding destination.

However, in the WiBro communication system, there is no support of the MAC layer, and the identifier used in the datalink layer has a 16-bit connection identifier (CID) unlike the 48-bit MAC address used in the Ethernet. . Therefore, in the conventional WiBro communication system, a flooding problem occurs in which a packet is transmitted without a specific destination. The flooding causes multiple unicasting to increase the amount of packets according to the number of terminals included in the multicast group. Therefore, in the conventional WiBro communication system, multiple unicasting occurs according to multicasting, and thus there is a problem in that performance of a network is degraded.

As described above, there is a problem in that network performance is deteriorated due to waste of resources during multicasting in a wireless communication system. In addition, conventionally, each terminal receives a duplicate multicast packet, and if there are many terminals receiving the multicast packet, there is a problem that time is delayed until the corresponding multicast packet is received.

In particular, in the conventional WiBro communication system, there is no way of knowing the destination address of the multicast packet, and thus, the base station cannot accurately transmit the received multicast packet to the corresponding terminal.

Accordingly, the present invention provides a method and a wireless communication system supporting multicasting for enabling resource efficient multicasting in a wireless communication system.

In addition, the present invention provides a method and a wireless communication system supporting multicasting to enable the multicast packet transmission to the terminal correctly and quickly.

The present invention provides a method for supporting multicasting in a terminal of a wireless communication system, the method including receiving a multicast assignment request (MCA-REQ) message, and a multicast packet from the received multicast assignment request message. Checking an IP address of the Internet Protocol; determining whether an IP address of the checked multicast packet is the same as an IP address of a service server providing a multicast packet to be received; And transmitting a response signal corresponding to the received multicast packet to a base station.

The present invention provides a method for supporting multicasting in a base station of a wireless communication system, the method comprising receiving a multicast packet and requesting a multicast allocation of a multicast IP address corresponding to the received multicast packet (MCA-REQ). A multicast assignment request message is transmitted to a terminal, and when a response signal is received from the terminal, a multicast IP address included in the response signal and a multicast IP address corresponding to the received multicast packet. And comparing the received data with each other and transmitting the received multicast packet to the terminal if the comparison result is the same.

In addition, the present invention is a wireless communication system supporting multicasting, comprising a terminal and a base station, the terminal receives a multicast assignment request (MCA-REQ) message, the received multicast assignment The IP address of the multicast packet is checked from the request message, and it is determined whether the IP address of the checked multicast packet is the same as the IP address of the service server providing the multicast packet to be received. Send a response signal corresponding to the received multicast packet to a base station, the base station receives the multicast packet, and sends a multicast IP address corresponding to the received multicast packet to the multicast assignment request message. And transmit to the terminal, and when a response signal is received from the terminal, When compared to a multicast IP address corresponding to the multicast packets, a multicast IP address and the received answer signal including the same result of the comparison, characterized in that the transmission of the received multicast packet to the mobile station.

The present invention has the advantage of performing resource efficient multicasting in a wireless communication system. Furthermore, the present invention reduces the delay time caused by duplicate packets in the network when providing multimedia data services such as video streaming, user created content (IPC), and IPTV in a wireless communication system. There is an effect that can provide a higher service.

Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to the accompanying drawings. In addition, detailed descriptions of well-known functions and configurations that may unnecessarily obscure the subject matter of the present invention will be omitted.

According to the present invention, a terminal of a wireless communication system receives a multicast assignment request (MCA-REQ) message and checks an IP address (Internet Protocol address) of a multicast packet from the received multicast assignment request message. Determine whether the IP address of the checked multicast packet is the same as the IP address of the service server providing the multicast packet to be received. If the determination result is the same, a response signal corresponding to the received multicast packet is transmitted to the base station. Send.

Hereinafter, an embodiment of the present invention will be described in detail with reference to the accompanying drawings.

1 is a diagram illustrating a wireless communication system supporting multicasting according to an embodiment of the present invention.

1, a multicast router 100, a control station (hereinafter referred to as 'ACR') 102, a base station (hereinafter referred to as RAS) 104 and one or more terminals (Subscribe Station: SS) The configuration of a wireless communication system including (106)-(110) is shown.

The multicast router 100 is connected to the local network and transmits an Internet group management protocol (IGMP) query message. In particular, in an embodiment of the present invention, the multicast router 100 transmits a multicast packet provided from a plurality of service servers (not shown).

The ACR 102 includes a multicast route table (hereinafter referred to as a "path table") for storing an interface in a terminal direction, that is, a multicast IP address (Internet Protocal Address) and a MAC address of the RAS 104. Accordingly, when the multicast packet is received from the multicast router 100, the ACR 102 checks the route table to determine whether there is a destination IP address, that is, a multicast IP address. If the multicast IP address is found as a result of the check, the ACR 102 obtains a MAC address corresponding to the multicast IP address from the route table, and transmits the multicast packet to the RAS having the obtained MAC address. Send.

The RAS 104 is connected to the ACR 102 to receive a multicast packet transmitted from the ACR 102. In addition, the RAS 104 transmits a multicast assignment request (hereinafter, referred to as 'MCA-REQ') message to the plurality of terminals 106 to 110 to the multicast group. To 110. In this case, according to an embodiment of the present invention, the RAS 104 transmits the MCA-REQ message after including the multicast IP address in the MCA-REQ message.

Accordingly, the configuration of the MCA-REQ message proposed in the present invention is shown in Table 1 below.

As shown in Table 1, the present invention adds a multicast IP address to a conventional MCA-REQ message. This is to allow the corresponding terminals to check whether they are polling for the multicast group to which they have subscribed using the MCA-REQ message.

Accordingly, the terminal 106 receiving the MCA-REQ message from the RAS 104 checks the multicast IP address from the received MCA-REQ message. And the terminal 106 is a service server that provides the multicast packet to receive the IP address (hereinafter referred to as 'IGMP IP'), namely the multicast group to which the identified multicast IP address subscribed via IGMP Check if it is same as IP address. The terminal 106 transmits a multicast assignment response (hereinafter referred to as 'MCA-RSP') message to the RAS 104 when the multicast IP is identical to its own IGMP IP. . According to an embodiment of the present invention, the MCA-RSP message includes the IP address determined to be the same.

The RAS 104 receives the MCA-RSP message from the terminal 106 and generates a multicast group table (hereinafter referred to as a 'group table') according to the multicast IP. In an embodiment of the present invention, one group table is generated per one multicast group, but this may be changed in various ways according to an embodiment of the present invention.

The RAS 104 allocates the same connection identifier (hereinafter referred to as "CID") to the terminals that have transmitted the MCA-RSP message. The RAS 104 maps the allocated CID to a multicast IP address and stores the mapping in the group table. Accordingly, the terminal transmitting the MCA-RSP message is registered in the group table of the RAS 104, and thus, the terminal transmitting the MCA-RSP message can receive a multicast packet from the RAS 104 according to the multicast group subscribed thereto.

Hereinafter, a signal flow diagram according to multicasting in a wireless communication system according to an exemplary embodiment of the present invention will be described with reference to FIG. 2.

Referring to FIG. 2, the terminal 106 generates the RAS 104 by generating an IGMP join message for multicast group subscription according to the Internet Group Management Protocol (IGMP) in step 200. Transmit to the ACR 102. The ACR 102 then receives the group join message and stores the MAC address of the RAS 104 and the corresponding multicast IP address according to the group join message. The ACR 102 transmits a group join message to the multicast router 100 in step 202.

Then, the multicast router 100 receives the group join message and transmits it to the service server. When the multicast packet is received from the service server, the multicast router 100 transmits the multicast packet to the ACR 102 in step 204. Subsequently, the ACR 102 receives the multicast packet, checks the IP address of the received multicast packet in a group table, and checks the MAC address corresponding to the IP address. The ACR 102 then transmits the multicast packet 206 to the RAS 104 having the checked MAC address in step 206. In this case, the multicast packet is encapsulated into an IP datagram having a multicast IP address through Generic Routing Encapsulation (GRE) according to an embodiment of the present invention. ) Is sent to RAS 104.

The RAS 104 receives the multicast packet to generate a multicast CID, and maps the generated multicast CID to a multicast IP address. In addition, the RAS 104 transmits the multicast IP address to the MS 106 by including the multicast IP address in the MCA-REQ message in step 208 to register the MSs in the multicast polling group.

In this case, the terminal 106 receiving the MCA-REQ message compares the multicast IP included in the MCA-REQ message with a pre-stored IGMP IP corresponding to the MCA-REQ message. If the multicast IP and the IGMP IP are the same as the result of the comparison, the terminal 106 transmits the multicast IP to the RAS 104 in the MCA-RSP message in step 210. Then, the RAS 104 compares the multicast IP address included in the MCA-RSP message with the multicast IP address corresponding to the received multicast packet, and determines that the RAS 104 is the same. 106). Accordingly, the terminal 106 is registered in a more resource-efficient manner in the multicast polling group managed by the RAS 104, so that the multicast packet according to the multicast group can be received without time delay.

Meanwhile, according to an embodiment of the present invention, the terminal 106 does not transmit an MCA-RSP message to the RAS 104 when the multicast IP and the IGMP IP are not the same as a result of the comparison. That is, the terminal 106 does not respond to the RAS 104 so that it is not registered in the multicast group.

According to an embodiment of the present invention, the RAS 104 may perform the following process when terminals join or leave a multicast group.

Hereinafter, a process of registering terminals in a multicast group table in a RAS according to an embodiment of the present invention will be described with reference to FIG. 3.

Referring to FIG. 3, the RAS 104 determines whether a new multicast packet is received in step 300. In other words, when a multicast packet is received, the RAS 104 determines whether this packet is a new multicast packet. In an embodiment of the present invention, since one group table is generated for each multicast group, the RAS 104 checks whether or not there is a group table corresponding to the received multicast packet, thereby receiving a new multicast packet. It can be determined whether the packet is multicast.

If the RAS 104 determines that it is a new multicast packet, the RAS 104 proceeds to step 302 and transmits an MCA-REQ message to all terminals. Here, the MCA-REQ message transmitted to the terminals includes a multicast IP address for a new multicast packet.

The RAS 104 determines whether an MCA-RSP message is received in step 304. That is, it is determined whether a response message according to the transmission of the MCA-REQ message is received.

According to an embodiment of the present invention, each terminal receiving the MCA-REQ message from the RAS 104 compares the multicast IP address included in the MCA-REQ message with the corresponding IGMP IP, and if it matches, the MCA-RSP message. Otherwise, it does not transmit an MCA-REQ message.

Accordingly, when the RAS 104 receives the MCA-REQ message, the RAS 104 adds the corresponding terminals to its multicast group table in step 306 by considering the terminals as the multicast group join request. The RAS 104 allocates CIDs to the terminals added to the group table in step 308. At this time, the CIDs allocated to the respective terminals are all the same according to the embodiment of the present invention. That is, terminals belonging to the same multicast group all have the same CID. Accordingly, when the RAS 104 receives a multicast packet corresponding to the multicast group, the RAS 104 checks the CID corresponding to the IP address of the multicast packet in the group table and transmits the received multicast packet to the terminals having the corresponding CID. Will be sent.

On the other hand, if it is determined in step 304 that the MCA-RSP message is not received, the RAS 104 proceeds to step 310 and determines whether the set time has elapsed. When the set time has passed, the RAS 104 proceeds to step 312 and discards the received new multicast packet. That is, if there is no response from all terminals for a predetermined time, the RAS 104 determines that there is no terminal to join the multicast group and discards the new multicast packet.

According to an embodiment of the present invention, the RAS 104 may additionally register the terminal in its multicast group table after transmitting the multicast packet. For a detailed description of this, hereinafter according to an embodiment of the present invention will be described with reference to Figure 4 showing a process of additionally registering the terminal in the multicast group table in the RAS.

In an embodiment of the present invention, the RAS 104 transmits an MCA-REQ message every 1 second to all terminals for all multicast groups registered in the multicast group table. Accordingly, the RAS 104 checks whether a timeout occurs every second, and performs the following process.

First, the RAS 104 determines whether a time out has occurred in step 400. When the RAS 104 times out, the RAS 104 proceeds to step 402 and transmits an MCA-REQ message to all terminals, and determines whether an MCA-RSP message is received in step 404.

When the MCA-RSP message is received, the RAS 104 determines that the corresponding UE that has transmitted the MCA-RSP message in step 406 is a new terminal, that is, a terminal that is not stored corresponding to the corresponding multicast IP in its group table. Determine the cognition.

In this case, if it is determined that the corresponding terminal is a new terminal, the RAS 104 proceeds to step 408 to add the terminal to the group table, and allocates CIDs to the corresponding terminals added to the group table in step 410.

If it is determined in step 406 that the terminal is not a new terminal, the RAS 104 considers that the terminal is already registered in its group table and maintains the current group table in step 412.

On the other hand, the RAS 104 performs the process of A, if the MCA-RSP message is not received in step 404. Here, A is used to show that step 404 of FIG. 4 and step 500 of FIG. 5 are connected. Hereinafter, the process of A will be described in detail with reference to FIG. 5 which shows a process for deleting a terminal from a multicast group table in a RAS according to an embodiment of the present invention.

Referring to FIG. 5, the RAS 104 determines whether the set time has elapsed in step 500. If the set time has elapsed, the RAS 104 checks the group table in step 502.

In step 504, the RAS 104 determines whether there is a terminal that has not transmitted an MCA-RSP message. Here, the expiration flag is stored as a field value corresponding to each terminal in the group table of the RAS 104 according to an embodiment of the present invention.

Next, the RAS 104 checks the group table again to determine whether there is a terminal having an expiration flag of 3 in step 508. In this case, if there is a terminal having the expiration flag of 3, the RAS 104 proceeds to step 510 and deletes the terminal from the group table.

As such, in the embodiment of the present invention, a minimum time of 3 seconds is required before the terminal is deleted from the group table of the RAS 104. However, the above process is performed after the UE transmits the multicast group leave message to the multicast router in advance, so that no particular problem occurs. However, when the terminal registered last in one multicast group table withdraws from the multitask, the RAS 104 only takes 3 seconds until the table is deleted.

Hereinafter, a method of using multiple unicasting for providing multicasting on a conventional WiBro and comparing the effects of the multicasting method proposed by the present invention will be described. For the comparison, it is assumed that the IEEE 802.16e model for NS-2 developed by the National Institute of Standards and Technology (NIST) is used and one multicast sender transmits data at 300 kbps. In order to examine the effect of increasing the number of terminals, it is assumed that the number of terminals is increased to 50 and using the parameters of Table 2 below.

Under the above assumptions, when comparing the multicasting method using the conventional multiple unicasting and the multicasting method proposed by the present invention, the multicast throughput according to the increase in the number of terminals is shown in Tables 3a and 3b. Differently shown as shown.

Table 3a is a graph showing the multicast processing speed when using the multicasting method according to an embodiment of the present invention.

In addition, Table 3b shows the multicast processing speed when the multicasting method using multiple unicasting is performed.

 In comparison with Tables 3a and 3b, the method according to the present invention can maintain a processing speed of 300 kbps despite the increase in the number of terminals. However, in the conventional method using multiple unicasting, the processing speed decreases as the number of terminals increases. This is because, in case of multiple unicasting, bandwidth is wasted due to the increase of redundant unicast traffic.

On the other hand, the method proposed by the present invention and the conventional multiple unicasting method also show a difference in the packet delay time (Packet delay time).

Table 4a shows packet delay times when using the multicasting method according to an embodiment of the present invention. Table 4b shows a packet delay time in case of using a conventional multiple unicasting method.

Comparing Table 4a and Table 4b, although the number of terminals increases in the method according to the present invention, the packet delay time is not significantly affected. However, in the conventional multiple unicasting method, the packet delay time increases as the number of terminals increases. Done. Meanwhile, the reason why the packet delay time graph is increased in 1 second in Tables 4a and 4b is that a packet drop occurs due to a collision of bandwidth allocation requests as the terminals simultaneously receive multicast packets in 1 second. .

1 is a diagram illustrating a wireless communication system supporting multicasting according to an embodiment of the present invention;

2 is a signal flow diagram illustrating multicasting in a wireless communication system according to an embodiment of the present invention;

3 is a diagram illustrating a process of registering terminals in a multicast group table in a RAS according to an embodiment of the present invention;

4 is a diagram illustrating a process of additionally registering a terminal in a multicast group table in a RAS according to an embodiment of the present invention;

5 is a diagram illustrating a procedure for deleting a terminal from a multicast group table in a RAS according to an embodiment of the present invention.

Claims (15)

A method of supporting multicasting in a terminal of a wireless communication system, Receiving a multicast assignment request (MCA-REQ) message, Checking an IP address (Internet Protocol Address) of a multicast packet from the received multicast allocation request message; Determining whether an IP address of the checked multicast packet is the same as an IP address of a service server providing a multicast packet to be received; If the determination result is the same, transmitting a response signal corresponding to the received multicast packet to a base station. The method of claim 1, And sending a multicast group join request message to the base station to receive the multicast assignment request message. The method of claim 2, The multicast group join request message is a group join message (IGMP join message) generated according to the Internet Group Management Protocol (IGMP).  The method of claim 1, And wherein the response signal includes an IP address of the received multicast packet. A method of supporting multicasting in a base station of a wireless communication system, Receiving a multicast packet, Transmitting a multicast IP address (Internet Protocol Address) corresponding to the received multicast packet in a multicast assignment request (MCA-REQ) message to a terminal; When a response signal is received from the terminal, comparing the multicast IP address included in the response signal with a multicast IP address corresponding to the received multicast packet; If the comparison result is the same, transmitting the received multicast packet to the terminal. The method of claim 5, The comparing may include identifying an IP address of a multicast packet included in the response signal; Determining whether a multicast group table corresponding to the identified multicast IP address exists; And if the multicast group table exists as a result of the determination, adding a connection identifier (CID) of the terminal to the multicast group table. The method of claim 6, Generating a multicast group table of the multicast IP address when the multicast group table does not exist as a result of the determination; And adding a connection identifier of the terminal to the generated multicast group table. The method of claim 6,  The step of adding the connection identifier of the terminal comprises the step of assigning the connection identifier to the terminal. In a wireless communication system supporting multicasting, Terminal, Includes a base station, The terminal receives a multicast assignment request (MCA-REQ) message, confirms an IP address (Internet Protocol Address) of a multicast packet from the received multicast assignment request message, and checks the checked multicast. It is determined whether the IP address of the packet is the same as the IP address of the service server providing the multicast packet to be received. If the determination result is the same, a response signal corresponding to the received multicast packet is transmitted to the base station. The base station receives a multicast packet, transmits a multicast IP address corresponding to the received multicast packet to the terminal by including the multicast allocation request message, and when a response signal is received from the terminal, And comparing the multicast IP address included in the response signal with the multicast IP address corresponding to the received multicast packet and transmitting the received multicast packet to the terminal if the comparison result is the same. system. The method of claim 9, And the terminal transmits a multicast group join request message to the base station to receive the multicast assignment request message. The method of claim 9, The multicast group join request message is a wireless communication system, characterized in that the group join message (IGMP join message) generated according to the Internet Group Management Protocol (IGMP).  The method of claim 9, The response signal comprises an IP address of the received multicast packet. The method of claim 9, When the base station compares the multicast IP address included in the response signal with the multicast IP address corresponding to the received multicast packet, the base station identifies the IP address of the multicast packet included in the response signal, It is determined whether a multicast group table corresponding to a multicast IP address exists. If the multicast group table exists as a result of the determination, a connection identifier (CID) of the terminal is added to the multicast group table. Wireless communication system, characterized in that. The method of claim 13, If the multicast group table does not exist as a result of the determination, the base station generates a multicast group table of the multicast IP address, and adds the connection identifier of the terminal to the generated multicast group table. Wireless communication system. The method of claim 13, The base station assigns the connection identifier to the terminal when adding the connection identifier of the terminal.

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